Development and Validation of Densitometry TLC Stability Indicating Method for Quantitative Determination of Azelastine Hydrochloride and Emedastine Difumarate in Their Drug Products

Aims: Stability indicating densitometry-TLC assay was established and validated for determination of azelastine hydrochloride (AZT) and emedastine difumarate (ETD) in the presence of their acid and oxidative degradants.
Methodology: Forced degradation was performed using 30% H2O2 and 5 M HCl. The method was based on thin-layer chromatographic separation of the two drugs from their degradants, using methanol- 10% ammonia (9.5:0.5, v/v) as developing system, followed by densitometric measurements of the intact drug spots at 292 and 283 nm, for azelastine hydrochloride and emedastine difumarate respectively.
Results: The linear range was 0.5 - 10.0 μg/spot, with mean recoveries of 100.09 ± 0.53% and 100.36 ± 0.40% for azelastine hydrochloride and emedastine difumarate respectively.
Conclusion: The proposed method was successfully applied for the routine quality control analysis of both drugs in laboratory prepared mixtures and commercially available preparations. The degradation products were identified by IR and MS and the pathways were illustrated. The method was validated according to ICH.